Method for producing a benthonic well

ABSTRACT

This invention relates to a method for production of oil and gas from an underwater formation with a remotely controllable production head positioned proximate the ocean floor. According to the method described, an apertured landing base is installed at the formation and a well casing attached to the lower end of the production head is lowered through the base into the well and landed on the base. Production tubing is then secured to a tubing hanger mandrel and lowered through the well and production head and landed in the production head. The production head is then plugged and the well produced through side outlets in the production head without connection to the structure at the ocean surface.

United States Patent Wakefield, Jr.

[54] METHOD FOR PRODUCING A BENTHONIC WELL Charles E. Wakefield, Jr., Dallas, Tex.

Atlantic Richfield Company, New York, NY.

[72] Inventor:

[73] Assignee:

[22] Filed: May 12,1969

21 Appl. No.: 823,734

Related US. Application Data [63] Continuation of Ser. No. 595,790, Nov. 21, 1966, which is a continuation-in-part of Ser. No. 498,851, Oct. 20, 1965, Pat. No. 3,332,481.

3,099,317 7/1963 Todd ..166/.6X

[451 May 16, 1972 Primary Examiner-lam A. Calvert Assistant Examiner-Richard E. Favreau Attorney-Donald W. Canady and Blucher S. Tharp [5 7] ABSTRACT This invention relates to a method for production of oil and gas from an underwater formation with a remotely controllable production head positioned proximate the ocean floor. According to the method described, an apertured landing base is installed at the fonnation and a well casing attached to the lower end of the production head is lowered through the base into the well and landed on the base. Production tubing is then secured to a tubing hanger mandrel and lowered through the well and production head and landed in the production head. The production head is then plugged and the well produced through side outlets in the production head without connection to the structure at the ocean surface.

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METHOD FOR PRODUCING ABENI'HONIC WELL RELATED APPLICATIONS FIELD oF- INVENTION This application relates to the production of petroleum from a formation underlying a body of water, and more particularly, relates to a method for landing and producing with an underwater production head at the ocean floor.

I BACKGROUND OFINVFNTION When drilling into and producing'from astratum containing oil and gas under high pressure, a device known as a Christmas tree is normally utilized .to control flow of oil and gas from the well during the period of natural flow. The Christmas tree comprises an assemblage of valves including generally, a master valve, one or more wing valves, and such flow constricting and gauging devices as'may be required in a particular well. The outer casingis normally cemented into the well with the casing spool, the tubing head, the casing head, and the various Christmas tree components connected to the outer casing by bolting: flanged fittings thereto. This, of course, requires working accessto the wellhead during installation.

in offshore production methods heretofore known the production head has been located at thesurface of the water on a platform where workmen can easily flange-up a wellhead and Christmastree. In deeper .water, however, such platforms are impractical and ithas been proposed to locate the production head on the floor of the body-of water. Installing a conventional Christmas tree on bottom, however, which has been done in some areas, necessarily requires costly diving operations.

it is therefore an object of my invention to provide a method for installing such production head beneath the water surface.

ltis also an object of my present invention to provide a method for installing a submarine production head on the ocean floor at relatively deep depths.

It is also an object of my present invention to provide a method for installing a submarine production head remotely from a floating vessel.

A further object of my invention is to produce a benthonic well with a production head installed on the ocean floor without connections to the structure from which drilling was accomplished and the production head installed.

Other objects and a fuller understanding of the invention may be had by referring to the following description and the appended claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an elevation'of my underwater production head showing its position relative to the well and submarine drilling base;

FIGS. 2a and 2b are divided longitudinal sectional views of the assembled production head showing the outer production head or mandrel and the inner tubing hanger mandrel assembly;

FIGS. 3 through 7 show the steps of the method for installing the production head in a well drilled into a formation underlying a body of water;

' FIG. 3 is a side elevation in diagrammatic form showing the manner in which the inner casing is hunglpreparatory to landing the production head;

FIG. 4 is a side elevation in diagrammatic form showing the production mandrel positioned on the surface casing landing mandrel just above the landing base;

FIG. 5 is adiagrammatic side elevation showing the equipment used to run the tubing into the well;

FIG. 6 is a diagrammatic side elevation illustrating the means used to plug the production head preparatory to bringing the well in;

FIG. 7 is a diagrammatic side elevation view showing the benthonic well in production;

FIGS. 8a and 8b are divided longitudinal sectional views of a modification of the production head shown in F 168. 2a and 2b employing a second string of tubing with an additional side outlet communicating therewith. 1

Referring to the drawings, the invention is illustrated with reference to an underwater production head 10 which is adapted to be operated remotely either from a land base or a nearby offshore structure through control lines. The production head 10 serves the purpose of controlling the flow of gas and oil from the well 14 which function is normally performed by a Christmas tree and wellhead in land based operations. The assembled production head 10 is installed on the ocean floor on landing base 18 from a drilling barge 16 so that it can subsequently be remotely controlled from land at the completion of the drilling operation when the top opening is plugged off above the tubing outlet.

in another embodiment of the above device the bore of the production head assembly shown in FIG. 2 is enlarged to permit drilling operations and the passage of easing therethrough, thus obviating the need for separate installation of the production head at the conclusion of the drillingoperation.

Referring now to FIG. 1, a landing base 18 with a funnel member 20 and a sleeve 22 which guide drilling tools and various well equipment through the landing base is positioned on the, ocean floor at the well opening. In a preferred practice, the base is hung off on wire lines under the vessel and the drill string run through the hole in the base to make sufficient hole in the ocean floor to receive the sleeve portions 22 and 22b and land the base on the oceanfloor. With the drill pipe still in the hole, the base is then lowered on the wire lines and guided to the ocean floor over the drill pipe. The lower portion 22b of the sleeve 22 is affixed to sleeve 22 in such a manner that the joint forms a seat on which the conductor pipe 24 rests as shown in FIG. 10 of U.S. Pat. No. 3,236,308 of William D. Leake, issued Feb. 22, 1966 on Ser. No. 19,722 filed Apr. 4, 1960. The wire lines connected to the base are then available for guiding drilling tools into the benthoic well. The surface pipe 26 is equipped with external lugs (not shown) which support the-surface pipe within the conductor pipe 24 in the manner shown inthe aforementioned U.S. Pat. No. 3,236,308. In situations where a conductor pipe and surface pipe are not used, the casing is supported'on the base or the aforementioned seat, on external lugs (not shown) provided on the upper portion of the casing. As shown in FIG. 1, the surface pipe 26 is provided at its upper extremity with a landing mandrel 29 onto which the blowout prevention equipment is latched during the drilling operation. The production mandrel 30, with the casing 59 connected to the lower end thereof, is supported on the upper end of the surface pipe landing mandrel 29 as shown in FIG. 1, with the casing 59 extending down into the surface pipe. The shouldered portion at the upper end of the splines 34 (FIG. 2b) rests on the top of the landing mandrel 29.

The production head 10 includes a production mandrel 30 which is clamped together in two pieces, the lower portion 32 of which may be provided with splines 34 and cemented into the surface pipe. The production mandrel 30 functions as one piece and can be constructed as one unit, however, as a prevention measure I prefer to divide the outer mandrel into two pieces as shown to facilitate removal of the upper part of the mandrel should the need arise after the lower portion 32 has been cemented into the surface pipe. A sealing member 58 is positioned between the production mandrel and the lower splined portion 32. Portion 32 is equipped with a baffle 36 beneath the clamps 38 which serves to protect the clamps from cement returns. The production mandrel has a latching neck 56 near its upper end onto which the blowout prevention equipment may be latched while the tubing 54 is being run into the well.

The production mandrel 30 is provided with a casing outlet 40 and a tubing outlet 42 through which latter outlet the flow of oil and gas from the well 14 is controlled. A casing flow line 44 is provided at the outlet 40 and a casing valve 46 is positioned at the outlet 40 and hydraulically actuated through fluid control lines 47. The casing outlet may be used initially to circulate drilling fluid from the well, however, it is normally closed during the period of natural flow. Valve 46 preferably is a conventional non-lubricated plug valve equipped with a conventional hydraulic actuator.

The tubing outlet 42 is equipped with a hydraulically actuated control valve 50 similar to casing valve 46, and a second spring loaded safety valve 52 held open with hydraulic pressure, which together control the flow of gas and oil from the well through the flow tube 54.

The production head has an outer or production mandrel 30 and an inner or tubing hanger mandrel 31 as shown in detail in FIGS. 2a and 2b. Water shutoff casing 59 is threaded to the lower end of the production mandrel 30 at 33, and supported within the base 18 when the mandrel 30 is landed on the ocean floor. The mandrel and casing 59 may be landed on the top of the surface pipe as shown in FIG. 1, or on the conductor pipe or base with external lugs as previously mentioned. In either situation, the casing and production mandrel are said herein to be landed on the base. After the casing 59 is cemented to the formation, production tubing 54 is threaded into the lower end of the tubing hanger mandrel at 68. An orientation cam 60 inside the production mandrel 30 is adapted to receive orientation lug 62 on the tubing hanger mandrel 31 only in such a manner that the side opening 64 in the tubing hanger mandrel 31 registers with the tubing outlet 42 in the production mandrel 30. ln FIG. 2b, the orientation cam 60 and the lug 62 have been rotated 180 for the ease of illustration. As best viewed in FIG. 8b, orientation lug 62 has an internal keyway 63 which is aligned with keyway 61 provided in the tubing hanger mandrel 31. A key held in place by set screw 73 is fitted in the aligned keyways 63 and 61 to prevent the orientation lug 62 from rotating relative to the tubing hanger mandrel 31.

The tubing hanger mandrel bore 65 is plugged above the side outlet 64 with any suitable means which can be inserted remotely, such as the Otis type "S" packing mandrel assembly 66 which can be fitted into sealing position on a wire line. The cap 67 of packer assembly 66 can be removed and a second packer 66b added to the packer assembly on an extension 69 to seal off tubing outlet 64.

Tubing 54 is threaded into a coupling member 68 which in turn is threaded to the lower end of the tubing hanger mandrel 31. The tubing and the tubing hanger mandrel are supported within the production mandrel with a suitable tubing hanger member such as the automatic tubing hanger 70, on internal tapered portion 72 of the production mandrel. The automatic tubing hanger 70 hangs the tubing in the production head automatically without the use of manually tightened ring nuts or locking screws. The hanger, supporting the tubing string, seats on a tapered bowl 72 in the tubing head and is locked against upward movement by spring dogs 75. As the hanger 70 enters the production mandrel 30, the spring dogs 75 surrounding the upper part of the hanger are retracted and the hanger slides down until, as shown in FIGS. 2b and 8b, the dogs spring automatically into the groove or shoulder 75a provided in the production mandrel. Downhole pressure from below the tubing hanger actuates or locks the automatic tubing hanger by moving the packing unit 77 upward which, in turn, locks the spring dogs securely into groove 75a.

During production, oil and gas flows through tubing 54 and up through tubing hanger mandrel bore 65, out the registering tubing outlets 64 and 42 through the hydraulically controlled valves 50 and 52 and thence through flow line 76 to storage tanks. Packer cups 78 and 79 which may advantageously be of the self sealing or pressure energized type, seal against leakage between the production mandrel and the tubing hanger mandrel at their tubing outlets. The tubing hanger seals 71 are the primary seals between the tubing and the casing against upward flow through the casing annulus 41 above casing outlet 40. Packer cup 79 also serves as a secondary seal behind primary seals 71, to restrict flow between the tubing and casing to the casing outlet 40. Packer cup 79 is supported by a thimble 80 which is supported on the automatic tubing hanger 70 by a sleeve 82. Packer thirnble 84 is supported in place by the safety joint part 86 which is threaded to the tubing hanger mandrel at 87.

A variation of the production head is shown assembled in FIGS. 8a and 8b. In this modification a macaroni string 122 is supported within the tubing hanger mandrel 31. A tubing hanger mandrel adapter 124 is threaded to the upper end of the tubing hanger mandrel 31 and has a macaroni hanger 126 threaded therein on which the inner or macaroni string of tubing 122 is hung with a coupling member 130. Packing member 128 seals off flow between tubing 122 and the tubing hanger mandrel above the tubing outlet 42, and sealing elements 129 serve as secondary seals. The upper end of the macaroni hanger 126 is socketed similar to the upper end of the head plug 88 and the safety joint 86 so that the tubing hanger mandrel or the macaroni string 122 can be removed on a socket coupling (now shown) attached to the drill string. The upper end 31a of the tubing hanger mandrel is provided with an additional outlet 132 which communicates with outlet 134 in the production mandrel, thus providing communication between the macaroni tubing 122 and the outlet 120. As an example of the second recovery techniques for which this macaroni tubing may be employed, gas may be injected into the outlet 120 and through the macaroni tubing to effect a gas lift.

Packers 136 and 138 (FIG. 8a) are provided above and below the macaroni outlet 120 to seal between the production mandrel 30 and the upper portion 127 of the tubing hanger mandrel. In FIG. 8b the tubing outlet 42 is shown in phantom since in this modification outlet 42 would not be in the same plane with the casing outlet 40 and macaroni outlet 120. In the modification shown in FIGS. 8a and 8b the production head apparatus below the tubing outlet 42 would be essentially the same as in the production head described above.

In operation the production mandrel is first landed on the surface casing landing mandrel with a suitable landing sub, then the assembled tubing hanger mandrel with tubing connected thereto is lowered into place on the drill pipe with the socket end of a safety joint attached to the lower end thereof, after which the plug 66 is set on a wire line. A head plug 88 is then lowered on the socket end of the safety joint (not shown) and screwed into the production mandrel. The head plug 88 is designed to limit upward movement of the tubing hanger mandrel in the event of a blowout and serves as a secondary seal above packer cup 78 and plug 66.

The casing 59 may be hung in one piece as previously described, or it can be hung in two sections as shown in FIGS. 3 and 4 by splicing the bottom of the upper section into the top of the lower section, with the production mandrel affixed to the upper end of the top section. With the blowout prevention equipment 92 latched to the latching neck 28 of the surface casing landing mandrel 29 the lower section of casing 59b is hung on a conventional casing hanger 94 which is lowered into the surface pipe on the drill pipe 96, as shown in FIG. 3. A suitable release tool 98 is used to release the drill pipe from the casing hanger.

A tubing tail 99 is run through the casing hanger and the lower section 59b of the casing is cemented up to the casing hanger. A flexible cement plug is provided to divide the cement from the drilling mud and a down swab 102 prevents the cement from coming back up the casing. A float collar 101 and a float shoe 103 are provided in the conventional manner at the lower end of the casing to prevent cement from coming back up the inside of the casing after displacement of the cement.

After the lower section of casing is cemented in the surface pipe the casing is sealed ofi' internally with a bridge plug or a cement plug 104 and the blowout prevention equipment removed from the wellhead, as shown in FIG. 4. The production mandrel 30 with the upper section of casing 59a threaded thereon is lowered into the surface pipe on the drill pipe with a landing sub 110. A suitable casing splice 106 is provided to splice the lower section 59b of the casing to the upper section 590 of the casing. A flexible slip joint 108 may be provided in the casing between the upper and lower sections of casing.

The tubing tail 99 is withdrawn to the barge to attach a second flexible plug and then the upper section 59a of the casing is cemented through a stage cement collar 112. Thus, the casing and the splined lower portion 32 of the production mandrel are cemented into the surface pipe 26 and surface casing landing mandrel 29. The bafi'le 36 prevents cement returns fromcontacting the clamp 38. The surface pipe and conductor pipe, when used, would have been previously cemented into the well.

When the production head is used as a drilling head, the casing is hung from the inside of the enlarged production mandrel, for example, on a donut hanger, and the surface casing is threaded to the lower end of the production mandrel.

The blowout prevention equipment 92 is replaced on the production mandrel by latching the blowout prevention equipment to the latching neck 56 of the production mandrel. The casing riser 118 which was used in the drilling operation is then lowered and latched into the upper end of the blowout prevention equipment 92. After the casing plug 104 is drilled out or retrieved, the tubing is hung on the tubing hanger mandrel and the tubing hanger mandrel lowered into the production mandrel, as shown in FIG. 5. The socket end 105 of the safety joint 86 is threaded to the drill pipe 96 and releasably latches the safety joint 86 of the tubing hanger mandrel to the drill pipe to lower the mandrel assembly into the well. The lower end of the tubing is provided with a special packer 114 which is a means of confining zone pressure. Above this packer a sliding side door 116 is provided for circulating mud out of the hole after the tubing is run into the casing.

Before the tubing hanger mandrel is lowered through the blowout prevention equipment, plug 66 with an extension 69 and second packer 66b which seals the bore of the tubing hanger mandrel below the tubing outlet, is lowered into the tubing hanger mandrel to seal off the tubing outlet of the tubing hanger mandrel until the mandrel is lowered through the blowout preventers and the tubing outlet put in communication with the tubing outlet valves 50 and 52. After the tubing hanger mandrel 31 is lowered into place, however, the plug 66 is pulled up to the barge and the second packer 66b and the extension 69 are removed and a cap 67 screwed into the plug 66 to seal off the tubing above the tubing outlet 64 and permit tubing flow through the outlet. A head plug 88 is then threaded into the production mandrel 30 with the socket end 105 of the safety joint attached to the drill pipe 96. This plug 88 serves as a secondary seal above the packer cup 78 and also is a secondary seal to the plug 66 as well as a safety device to prevent the tubing hanger mandrel from blowing out of the hole.

At the conclusion of the drilling and cementing operations and after the well is brought in, the drill pipe and easing riser are withdrawn to the barge and the blowout prevention equipment retrieved. The production of fluid from the well is then controlled remotely from a shore control center or a control barge. Flow line 76 is connected to the fail-safe valve 52 and run on the ocean floor with the safety valve control line 49 to a tank (not shown). The casing outlet hose 44 and the remainder of the control lines are then blanked off and dropped on bottom. A buoy marker 120 is attached to the blanked off control lines and easing outlet hose as shown in FIG. 7.

Although I have described my present invention with a certain degree of particularity in order to set forth the best mode of operation, it is to be understood that my invention is not to be limited to the details set forth.

I claim:

1. In a method for producing a well drilled in the earth underlying a body of water from a structure on said body of water, the steps comprising:

a. installing an apertured landing base on the earth at the well opening,

b. securing well casing to the lower end of a production head,

c. lowering said production head with said casing from said structure on said body of water into said well through said apertured landing base,

d. landing said casing and said production head on said landing base, securing production tubing to the lower end of a tubing hanger mandrel,

e. lowering said tubing hanger mandrel with said tubing from a structure on said body of water into said production head whereby said tubing extends into said casing,

f. hanging and locking said tubing hanger mandrel within said production head,

g. plugging said production head to prevent flow through the top of said production head, and

h. producing well fluids from said well tubing through a side outlet in said production head.

2. The method of claim 1 including the step of operatively connecting said tubing to a flow line through said side outlet in said production head.

3. In a method for producing a well drilled in the earth underlying a body of water from a structure on said body of water, the steps comprising:

a. installing an apertured landing base on the earth at the well opening,

b. landing a well casing and a production head on said landing base,

c. securing production tubing to a tubing hanger mandrel,

d. lowering said tubing hanger mandrel with said tubing from said structure into said production head whereby said tubing extends into said casing,

e. landing said mandrel on a shoulder in said production head,

f. locking said mandrel, within said production head to prevent upward movement of said mandrel relative to said production head, and

g. thereafter plugging said production head,

h. producing well fluids from said tubing through a side outlet in said production head.

4. In a method for drilling and producing a well drilled in the earth underlying a body of water from a structure on said body of water, the steps comprising:

installing an apertured landing base on the earth at the well opening with wire lines,

reentering said well with drilling tools using said wire lines as guide lines,

landing well casing and a production head on said landing base,

securing production tubing to a tubing hanger mandrel,

lowering said mandrel with said tubing from said structure into said production head whereby said tubing extends I into said casing,

landing said mandrel on a shoulder in said production head,

locking said mandrel with respect to said production head to prevent upward movement of said mandrel relative to said production head,

plugging said production head,

operatively connecting said tubing to a flow line through a side outlet in said production head, and

controlling flow of well fluids into said flow line through said production head side outlets with flow control valves operatively connected to said production head at said side outlets. 

1. In a method for producing a well drilled in the earth underlying a body of water from a structure on said body of water, the steps comprising: a. installing an apertured landing base on the earth at the well opening, b. securing well casing to the lower end of a production head, c. lowering said production head with said casing from said structure on said body of water into said well through said apertured landing base, d. landing said casing and said production head on said landing base, securing production tubing to the lower end of a tubing hanger mandrel, e. lowering said tubing hanger mandrel with said tubing from a structure on said body of water into said production head whereby said tubing extends into said casing, f. hanging and locking said tubing hanger mandrel within said production head, g. plugging said production head to prevent flow through the top of said production head, and h. producing well fluids from said well tubing through a side outlet in said production head.
 2. The method of claim 1 including the step of operatively connecting said tubing to a flow line through said side outlet in said production head.
 3. In a method for producing a well drilled in the earth underlying a body of water from a structure on said body of water, the steps cOmprising: a. installing an apertured landing base on the earth at the well opening, b. landing a well casing and a production head on said landing base, c. securing production tubing to a tubing hanger mandrel, d. lowering said tubing hanger mandrel with said tubing from said structure into said production head whereby said tubing extends into said casing, e. landing said mandrel on a shoulder in said production head, f. locking said mandrel, within said production head to prevent upward movement of said mandrel relative to said production head, and g. thereafter plugging said production head, h. producing well fluids from said tubing through a side outlet in said production head.
 4. In a method for drilling and producing a well drilled in the earth underlying a body of water from a structure on said body of water, the steps comprising: installing an apertured landing base on the earth at the well opening with wire lines, reentering said well with drilling tools using said wire lines as guide lines, landing well casing and a production head on said landing base, securing production tubing to a tubing hanger mandrel, lowering said mandrel with said tubing from said structure into said production head whereby said tubing extends into said casing, landing said mandrel on a shoulder in said production head, locking said mandrel with respect to said production head to prevent upward movement of said mandrel relative to said production head, plugging said production head, operatively connecting said tubing to a flow line through a side outlet in said production head, and controlling flow of well fluids into said flow line through said production head side outlets with flow control valves operatively connected to said production head at said side outlets. 